The trash talking began early, before the first beers, which is very early when this crew gets together each year.

They were gathered on a hillside at George Wright Golf Course early one recent morning, 80 blue shirts and 80 black, for a group photo before the beginning of the Parkway Cup. As they squished to fit in the photographer’s frame, one of the Roslindale guys in black began complaining that the West Roxbury team in blue was taking up too much space in the photo.

“That’s because they need the extra space for their heads,” one of the Roslindale guys shouted.

It was on.

In the long history of interneighborhood rivalries in Boston, the friction between West Roxbury and Roslindale — neighbors in the city’s southwest corner who have shared the Parkway youth sports program for generations — can be simplified to this: Roslindale natives tend to view West Roxbury as full of “rich” snobs in single-family homes who believe they’re better than them, while West Roxbury long treated Roslindale like its gritty younger brother, a neighborhood full of three-deckers and “Rozzie rats.”

“What it comes down to is they had two toilets and we had one,” said Doug McClure, 54, a proud “Rozzie rat” in a black golf shirt.

Like most rivalries, this one is largely friendly, slightly adorable, and mostly ridiculous. But for those who have grown up in it, it is unquestionably real. Or at least it was.

McClure is a longtime realtor in both neighborhoods, and he said that back when he was looking to open his regional office in the early ’90s, he and his partner chose West Roxbury because families there would not list with a brokerage firm in Roslindale. The reverse, he said, was not true.

Back then, the classic story was that if you “made it” in Roslindale, you moved to West Roxbury. Chris Warren was 14 when his family made that move. Now 29, when someone asks where he is from, he’ll get looks from his friends.

“If I say I’m from Roslindale, my West Roxbury friends will say, ‘You’re from West Roxbury.’ But if my Roslindale friends hear me say I’m from Roslindale, they’ll tell me I can’t say that because I’m a sellout.”

But today, due to a red-hot real estate market in Roslindale, that big brother-little brother relationship has been blurred. Gentrification has crept into Roslindale Square — old-timers refuse to call it by it’s relatively new “yuppie” name, Roslindale Village — and housing prices in Roslindale are, in many instances, outpacing West Roxbury.

Between 2005 and 2013, the median price of a single-family home in West Roxbury declined by nearly 10 percent, while in Roslindale that number rose nearly 9 percent, according to the Warren Group. The median price of a single-family in Roslindale in 2013 was $425,000, which is $20,000 more than in West Roxbury.

But there remain broad socioeconomic differences between the two communities. West Roxbury is Boston’s version of a suburb, with leafy streets filled with the homes of cops and firefighters and retirees. Sections of Roslindale are nearly identical, but other parts are much more urban, with three-deckers, public housing developments, and a famously gritty stretch of Washington Street that runs to Forest Hills Station.

Which brings us to the point of the golf tournament, which is not simply an opportunity for guys from the two neighborhoods to bust each other’s chops and fight over the Parkway Cup (which is won each year by the West Roxbury team, then promptly stolen by the Roslindale team).

The event is a fund-raiser for a nonprofit called “Parkway In Motion,” which seeks to bring the two neighborhoods together in social settings, something that has largely been absent in their relationship.

“Without this sort of thing, there’d be almost no interaction between these two neighborhoods,” said Chris Devlin, a 29-year-old from West Roxbury who is the current president of the organization.

Jonathan Wiggs/Globe staff

David Giordano and Eric Hanafin of Roslindale met some friends, with George Kehayias of West Roxbury in the back.

Parkway In Motion has hosted such events as an Easter egg hunt and trick-or-treating for kids, as well as basketball and cornhole tournaments, with plans for more, including a big Parkway reunion.

And it is the pride people feel for their respective neighborhoods — the very basis of the rivalry — that drives people to get involved.

“We think we have the best neighborhood in the city. They think they have the best,” said Ryan Mason, a Boston police detective from West Roxbury who founded the organization in 1998. “That competitive drive is what makes people want to give back to the kids who are growing up like they did.”

It is that same competitive drive that makes the trash-talking at the Parkway Cup ruthless, the classic Boston take-’em-out-at-the-knees sense of humor that rules on the street corner and in the locker room but can’t be printed in a family newspaper.

It was all, of course, in good fun. The rivalry, most say, has been dialing down for some time, and took a big hit after Roslindale High School graduated its last class in 1976 and West Roxbury High School no longer had a nemesis.

But “there’s no question we didn’t like each other,” said Tom Maguire, a 47-year-old from West Roxbury. “You’d go to the Holy Name dance and you’d have the West Roxbury kids in one area and the Roslindale kids in another. And we might have known each other, might have played sports together, but once somebody said something, it was battle on.”

Like many rivalries, what feels real in youth disintegrates in adulthood. Many of those at the recent golf tournament went to the same high schools and held teenage keg parties together in the Arnold Arboretum, which was considered neutral ground. There were huge contingents in the tournament from Catholic Memorial, Boston Latin Academy, and Boston Latin School, where Mason and many of those who helped found the organization met. As such, the day felt more like a reunion than a Red Sox-Yankees game.

By 10 a.m., the young woman who was driving around the course with giant coolers full of beer returned to the clubhouse with a wad of cash, empty coolers, and a look that said she was seriously impressed.

“These guys can drink,” she declared.

But at the bottom of it all, one thing was very real: Both sides wanted to win the tournament. Roslindale has long blamed its losing streak on the fact that the West Roxbury team is always in charge of adding up the scores. “That’s because we know how to add,” explained Mason, the founder.

When the round was over, the two teams repaired to the Emerald Society of the Boston Police in Roslindale for a banquet and a fight over the math on the final tally.

“Things are getting tense at the scorer’s table,” said Brendan Greally, a 37-year-old state attorney from Roslindale who helped found the organization. “This year, we have two black shirts and two blue shirts counting.”

Once again, West Roxbury had won. And once again, the Parkway Cup mysteriously disappeared later that night.

It has since reappeared on its own Facebook page, where photos show it traveling around the city — in a nail salon, posing in front of the skyline — as a hostage of the Roslindale team.